Send to

Choose Destination
Nucleic Acids Res. 2017 Jul 27;45(13):7581-7592. doi: 10.1093/nar/gkx507.

5΄-Vinylphosphonate improves tissue accumulation and efficacy of conjugated siRNAs in vivo.

Author information

RNA Therapeutics Institute, University of Massachusetts Medical School, 01605 Worcester, MA, USA.
Program in Molecular Medicine, University of Massachusetts Medical School, 01605 Worcester, MA, USA.
Department of Medicine, University of Massachusetts Medical School, 01605 Worcester, MA, USA.


5΄-Vinylphosphonate modification of siRNAs protects them from phosphatases, and improves silencing activity. Here, we show that 5΄-vinylphosphonate confers novel properties to siRNAs. Specifically, 5΄-vinylphosphonate (i) increases siRNA accumulation in tissues, (ii) extends duration of silencing in multiple organs and (iii) protects siRNAs from 5΄-to-3΄ exonucleases. Delivery of conjugated siRNAs requires extensive chemical modifications to achieve stability in vivo. Because chemically modified siRNAs are poor substrates for phosphorylation by kinases, and 5΄-phosphate is required for loading into RNA-induced silencing complex, the synthetic addition of a 5΄-phosphate on a fully modified siRNA guide strand is expected to be beneficial. Here, we show that synthetic phosphorylation of fully modified cholesterol-conjugated siRNAs increases their potency and efficacy in vitro, but when delivered systemically to mice, the 5΄-phosphate is removed within 2 hours. The 5΄-phosphate mimic 5΄-(E)-vinylphosphonate stabilizes the 5΄ end of the guide strand by protecting it from phosphatases and 5΄-to-3΄ exonucleases. The improved stability increases guide strand accumulation and retention in tissues, which significantly enhances the efficacy of cholesterol-conjugated siRNAs and the duration of silencing in vivo. Moreover, we show that 5΄-(E)-vinylphosphonate stabilizes 5΄ phosphate, thereby enabling systemic delivery to and silencing in kidney and heart.

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Silverchair Information Systems Icon for PubMed Central
Loading ...
Support Center